Sensitive detection of biological and chemical species is important in various fields, such as, for example, forensic analysis, environmental monitoring and clinic diagnostics. For instance, sensitive detection of cocaine may be critical for law enforcement and clinical diagnostics.
Aptamers have been developed to detect a variety of molecular targets including, for example, small molecules, nucleic acids, proteins and cancer cells. Aptamers are oligonucleotides with ligand-binding ability.
Various aptamer sensors based on colorimetric, electrochemistric and bulk fluorescence assay have been developed for several targets, including for cocaine detection. (Liu et al., J. Am. Chem. Soc. 2007, 129, 8634-8643; Liu et al., J. Angew. Chem. Int. Ed. 2006, 45, 90-94; Stojanovic et al., J. Am. Chem. Soc. 2002, 124, 9678-9679; Baker et al., J. Am. Chem. Soc. 2006, 128, 3138-3139; Stojanovic et al., J. Am. Chem. Soc. 2001, 123, 4928-4931; Stojanovic et al., J. Am. Chem. Soc. 2000, 122, 11547-11548; Shlyahovsky et al., J. Am. Chem. Soc. 2007, 12,3814-3815; and Liu et al., Anal. Chem. 2007, 79, 4120-4125.)
However, reported aptamer sensors either exhibit relatively low detection limits, or low detection sensitivity, or involve complicated sample preparation and large sample consumption. Accordingly, there is a need for simple and sensitive detection methods using aptamer sensors.